Fireplace heat exchanger

ABSTRACT

An improved fireplace heat exchanger apparatus having one or more generally first hollow members, wherein each first member has an internally disposed second hollow member thereby creating an annular space between the interior surface of the first hollow member and the exterior surface of the second hollow member. Ducting is provided to direct air/gas flow through the heat exchanger in a controlled, counter-flow manner. The interior portion of the second hollow member is configured to accept a flow of a heat transfer medium for transferring heat energy to a desired location while the annular space is configured to accept a flow of hot combustion gasses from the combustion chamber and direct it toward a chimney. A nozzle disc located in the annular passageway proximate the inlet of hot combustion gasses causes the gasses to circulate within the annular passageway to enhance heat transfer to the second hollow member.

BACKGROUND OF THE INVENTION

The present invention relates generally to fireplace accessories and, more particularly, to a heat exchanger apparatus adaptable to a wide array of fireplace sizes and useful for improving the heating efficiency of a fireplace,

Conventional fireplaces are inefficient sources of heat for the room in which they are located as the majority of the heat generated by the combustion process escapes through the chimney. Fireplace fires also require large volumes of combustion air, which if drawn from the interior space of the room, result in significant heat loss from the room as heated room air is also exhausted through the chimney. Cold air drafts in the interior space also result since the heat loss through the chimney causes cold air to be drawn in from the outside though door and window openings.

In an effort to increase the efficiency of fireplaces, fireplace inserts have been used. These devices generally comprise a large metal box situated partially within the fireplace and extending into the room in which the fireplace is located. Wood or other fuel is burned within the large metal box, which has openings for supplying combustion air and for expelling combustion gasses to the chimney. Room air circulated around the large metal box is heated and returned to the room without commingling with the combustion air stream. While such inserts have been designed to retain the visual appeal and rustic charm of an open flame, their heat transfer efficiency is limited, allowing substantial amounts of energy to be exhausted through the chimney to the outside. Furthermore, in operation the portions of the large metal box adjacent to the room tend to become extremely hot, which can be very hazardous if small children are present.

U.S. Pat. No. 4,357,930 and its progeny disclose a fireplace heating system for heating the room air incorporating a compact heat exchanger mounted at the top portion of the combustion chamber of the fireplace and extending across the location where the chimney flue connects with the top portion of the combustion chamber. A conventional fireplace door may be used to prevent room air from being exhausted through the chimney and isolate hotter portions of the fire from accidental contact by room occupants. A fan is provided for circulating room air through the heat exchanger in a manner so that the hot combustion gases heat up the room air being circulated therethrough without commingling. The design of the compact heat exchanger directs hot combustion gasses through torturous pathways to increase heat transfer, the complex design of the pathways results in increased fabrication costs for the heat exchanger assembly compared to more conventional heat exchange methods.

It would be desirable to provide an improved fire place heat exchanger apparatus suitable for use in existing or newly constructed fireplaces that further increases thermal efficiency of a fireplace, reduces the amount of heat energy exhausted through the chimney, and that can be economically fabricated from inexpensive yet durable materials.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an improved heat exchanger device that increases the efficiency and performance of fireplace heating systems thereby enabling a fireplace to effectively heat a home or provide a significant supplemental heat source,

It is another object of the present invention to provide a heat exchanger apparatus for use in a fireplace to provide a supplemental heat system for an enclosed building. The present invention is particularly adaptable to homes heated by heat pumps or other systems for which a supplemental heating system is particularly desirable when outside temperatures are cold (e.g., below 40 F.).

It is another object of the present invention to provide a heat exchanger apparatus for use in a fireplace that segregates combustion air flow from the room heating air flow thereby eliminating loss of heated room air through the chimney.

It is a further object of the present invention to provide a heat exchanger apparatus for use in a fireplace that is readily adaptable for heating room air in an adjacent room or a liquid heat transfer medium for heating a room area remotely located from the fireplace.

It is a further object of the present invention to provide a heat exchanger apparatus that is easily adapted for use in a variety of fireplace sizes and arrangements, including free-standing fireplaces, and in conjunction with existing doors covering fireplace openings.

It is a still further object of the present invention to provide a heat exchanger that is capable of lowering flue gas temperatures to the extent that alternate, preferably less expensive flue materials may be used thereby offsetting costs of the heat exchanger apparatus.

It is a still further object of the present invention to provide an improved fireplace heat exchanger apparatus that is durable in construction, inexpensive of manufacture carefree of maintenance, easily assembled, and simple and effective to use.

These and other objects are achieved by providing an improved fireplace heat exchanger apparatus incorporating one or more generally first hollow members located in the combustion chamber generally situated adjacent the rearward wall of the combustion chamber. The longitudinal axes of the hollow members are oriented generally vertically. Each first hollow member has an internally disposed second hollow member thereby creating an annular space between the interior surface of the first hollow member and the exterior surface of the second hollow member. Ducting is provided to direct air/gas flow through the heat exchanger in a controlled manner. The interior portion of the second hollow member is configured to accept an air flow from a room and returning it thereto while the annular space is configured to accept a flow of combustion gasses from the combustion chamber and direct it toward a chimney. Alternatively, a heat conducting liquid may be directed through the interior portion of the second hollow member and used to transport heat energy to a remote location. The respective flows are directed through the heat exchanger in a counter-flow arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:

FIG. 1 shows a side elevation view of a typical fireplace with the present invention located therein;

FIG. 2 is a front elevation view of the invention as it used in a fireplace.

FIG. 3 is a detailed view of the nozzle disc used in the heat exchanger assembly of the present invention;

FIG. 4 is a plan view of the heating medium supply and return conduits, and

FIG. 5 is an elevation view of a first alternative embodiment of the present invention wherein the heat exchanger core is of simplified construction.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art and they will not therefore be discussed in significant detail. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application of any element may already by widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail, when referring to the figures, like parts are numbered the same in all of the figures, unless otherwise noted.

In FIG. 1, there is shown a side elevation view of a typical fireplace 5 comprising a combustion chamber 10 having a front opening 12, a back wall 14, a pair of side walls 16, a hearth 18, and a chimney flue 20 connected to the top portion of the combustion chamber 10 by a throat 19, which is typically damper controlled. The combustion gases are discharged through the chimney flue 20 by way of the throat 19. Preferably, fireplace 5 includes a means for supplying relatively cold outside air to a hearth opening, and, to this end, there is provided a combustion air supply opening 11 in hearth 18 through which outside air may flow to supply combustion air for a burner located in the fireplace.

There is also disclosed in FIG. 1 a suitable type of gas log burner 30 for producing heat energy which is supplied with heating gas from an external source. These gas log burners are well known in the art and various suitable alternate types may be employed. Also provided is a conventional fire screen assembly 24 which closes and substantially seals the front opening 12, thereby separating combustion chamber 10 from the room area. Fire screen assembly preferably includes glass doors 26 that allow room occupants to observe the flames and that may be opened to access the combustion chamber 10 or for cleaning the glass. Air flow distributor 23 is positioned generally near hearth 18 to direct the flow of combustion air from the air supply opening 11 generally forwardly in the combustion chamber to create an air washing effect on the interior surface of the fire screen assembly glass thereby helping maintain visibility through the screen assembly. Combustion air then swirls within the combustion chamber 10 and is supplied to burner assembly 30. The hot combustion gases produced by the burner 30 will flow upwardly from the location of the burner combustion immediately above the hearth 18, said upwardly flowing gases being confined by the back and side walls 14, 16 of the fireplace and the glass screen 24. Fireplace elements are well known in the art and are discussed extensively in U.S. Pat. Nos. 4,357,930, 4,471,756, and 6,047,695, all by Eberhardt and which are incorporated in their entirety herein.

In accordance with the invention, there is provided a heat exchanger assembly 40 comprising one or more elongate heat exchanger cores 42 and means for mounting the same within combustion chamber 10, generally adjacent to back wall 14 and preferably vertically oriented Heat exchanger assembly 40 preferably incorporates an even number of heat exchanger cores 42 to enable efficient room air and combustion gas connections with the heat exchanger assembly 40. Flue baffle 22 is positioned to extend across the throat 19 in the top portion of the combustion chamber 10 to seal the connection between combustion chamber 10 and chimney flue 20. At least one flue opening 28 is provided in baffle 22 to provide combustion gasses created when the gas log burner 20 is in operation a controlled passage from combustion chamber 10 to chimney flue 20.

Elements of the heat exchanger assembly 40 may be held in position by anchoring tabs (not shown) secured directly into the walls 14, 16 of the fireplace which provide connection points for elements of the heat exchanger assembly. Such anchor tabs are suitable for use in fireplaces being modified to use the present invention or fireplaces initially constructed to use the invention. Alternatively, a free-standing support structure may be provided to enable the heat exchanger assembly 40 to be self-supporting within the fireplace, thereby eliminating the need to breach the interior walls of the fireplace with anchor bolts. The design of a free-standing support structure is ideally suited for retrofit applications and is, therefore, adjustable to suit a variety of fireplace sizes and configurations. Materials selected for support members, whether a free-standing frame or anchor tabs, are typically iron or steel and are selected for durability in when exposed to hot combustion gasses in the fireplace and relatively low cost.

Referring now to FIG. 2, an elevation view of heat exchanger assembly 40 comprising four heat exchanger cores 42 is shown as configured for use in a typical fireplace. The cores 42 shown in preferred embodiment are generally straight between opposing ends, arranged generally parallel and generally vertically positioned adjacent the back wall 14 of the combustion chamber 10. Each heat exchanger core 42 includes an elongate inner hollow member 44 surrounded by a substantially coextensive outer hollow member 46 forming an annular passageway 48 therebetween. Both hollow members 44, 46 preferably have generally circular cross-sections to allow smooth flow of combustion gasses and the heat transfer medium (air in the preferred embodiment described herein), though other shapes may be used with reasonable effectiveness. Each core is configured to accept flow of combustion gasses and heat transfer medium in a counter-flow arrangement, that is, the direction of flow of heat transfer medium in inner hollow member 44 is in a direction generally opposite of the flow of combustion gasses through the outer hollow member 46 for improved heat exchange performance.

Hot combustion gasses enter the outer-most heat exchanger cores near the top of the heat exchanger assembly, shown as double flow arrows in FIG. 2. After passing through the heat exchanger cores, the hot combustion gasses are collected in a combustion gas plenum 27 and discharged into the chimney through flue opening 28. As the conventional throat opening 19 is sealed in the present invention by the presence of flue baffle 22, all hot combustion gasses are directed through the heat exchanger assembly 40 prior to being discharged into the chimney flue.

Each heat exchanger core 42 is made of a materials to provide a highly heat conductive arrangement. To that end, inner hollow member 44 is constructed of a heat conductive material, such as aluminum, effectively conduct heat from the hot combustion gasses flowing through the annular passageway 48 to the heating medium flowing through the inner hollow member 44. Outer hollow member 46, which is directly exposed to the combustion occurring at burner 30, is likewise constructed of a highly heat conductive material, but one that is also more suitable for the combustion chamber environment, such as steel and, more specifically, stainless steel.

In the preferred embodiment, the heat exchanger assembly 40 is configured such that inlet and outlet openings for the inner hollow members 44 and the annular passageways 48 are generally adjacent and proximate a common end of the assembly 40. For illustrative purposes, two heat exchanger cores shown in FIG. 2 are identified with subscripts “a” and “b,” useful for describing the various flows occurring within the heat exchanger cores. It is to be noted that the subscripts do not indicate that the designated heat exchanger cores, or any parts thereof differ from those described using the same numeric only identifiers. When generally straight heat exchanger cores are used, adjacent pairs of cores 42 a, 42 b are connected in a manner to provide generally U-shaped flow paths within each of the hollow members. These connections are in the form of turnaround plenums. Hot combustion gasses are collected from the outlet end of first annular passageway 48 a in combustion gas turnaround adapter 62 and supplied to the inlet end of second annular passageway 48 b. Guide vanes within the combustion gas turnaround adapter 62 smooth the flow of gasses to maintain a portion of the gasses' rotational momentum as the gasses enter second annular passageway 48 b. Similarly, the heat transfer medium is collected from the discharge of a first inner hollow member 44 b and discharged to a second inner hollow member 44 a in a heating medium turnaround adapter 64. As can be observed in FIG. 2, heating medium turnaround adapter 64 is positioned at an end of the adjacent heat exchanger cores 42 a, 42 b while combustion gas turnaround adapter 62 is positioned slightly inwardly along the heat exchanger cores. Those skilled in the art will recognize that by selecting high thermal conductivity materials of construction for turnaround adapters 62, 64, the overall heat transfer between the fireplace and the heat transfer medium will be further increased. In the preferred embodiment, the combustion gas turnaround adapter 62 is constructed of the same stainless steel material as the outer hollow members 46. The heating medium turnaround adapter is 64 constructed from a cast aluminum material.

The aluminum inner hollow members 44 and other aluminum parts of the heat exchanger cores 42, such as the heating medium turnaround adapters 64, are anodized flat black. This improves the heat transfer properties of these parts by improving the heat transfer coefficient thereof. The overall heat transfer effectiveness of the heat exchanger assembly 40 is improved by the addition of a radiant energy reflector 50 (shown also in FIG. 1) to a portion of the heat exchanger assembly 40. The radiant energy reflector 50 may be in the form of a reflective covering, such as polished stainless steel or the like, on at least a portion of the outer hollow members 46. By positioning this radiant energy reflector 50 on the portion of the heat exchanger core adjacent to the burner, radiant heat energy from the combustion flames of burner 30 is thereby directed toward the room to be heated. Radiant energy reflector 50 may also be in the form of a material selection and/or exterior surface treatment of the outer hollow members 46 to provide the desired surface reflective characteristics.

Each heat exchanger core 42 is constructed and arranged to increase the dwell time of hot combustion gasses in the annular passageway thereby increasing the heat transfer between the relatively hotter combustion gasses and the relatively cooler heating medium. The object is to extract as much thermal energy as possible in a relatively compact space. By doing so, materials of construction for the chimney flue can be selected having to withstand much lower temperatures, as low as 150F, thereby allowing less expensive materials to be used for the chimney flue, such as PVC. To this end, the heat exchanger cores are configured to cause a vortex flow of the combustion gases as they flow through the annular passageway. The vortex flow is caused by at least one nozzle disc 70, which is connected to the inner and outer hollow members and positioned proximate to the inlet end of the annular passageway 48. As hot combustion gasses pass through nozzle disc 70, the gasses are forced to swirl about the annular passageway, generally circulating around the inner hollow structure 44 as the gasses proceed along the length of the heat exchanger core 42. Referring to FIG. 2, combustion gasses flowing through first heat exchanger core 42 a rotate generally counterclockwise, when viewed from above; about the inner hollow member 44 a as the gasses downwardly traverse the annular passageway. On the upward return pass through second heat exchanger core 42 b, the gasses spin generally in a clockwise direction about the inner hollow member 42 b, again when viewed from above. The direction of spin for the combustion gasses in the annular passageways is selected to be aided by the Coriolis effect of the earth's rotation, further enhancing the spinning motion of the combustion gasses traversing through the annular passageways.

FIG. 3 shows details of the nozzle disc 70 which is positioned proximate to the inlet end of each annular passageway 48. Nozzle disc 70 is of generally planar circular construction, having an outer perimeter 72 generally matching the inner perimeter of outer hollow member 46, and an inner opening structure 74 through which the inner hollow member 42 passes. In the preferred embodiment, inner and outer hollow members 44, 46 and nozzle disc 70 are arranged along a common centerline corresponding to the longitudinal axis of the hollow members 44, 46. A plurality of vane structures 76 are arranged generally radially about the centerline. The vane structures include a penetration 73 through the nozzle disc structure and a flow directing vane 75 positioned such that hot combustion gasses passing through the penetrations impinge on the flow directing vane and are deflected. Each flow directing vane is angled approximately 30 degrees from the plane of the nozzle disc, but those skilled in the art will recognize that a wide variation in the angle of inclination can be used without deviating from the functional objective of the nozzle disc 70. Gaps between the inner and outer hollow member 44, 46 walls and the nozzle disc 70 are minimized by a tight-fitting interface so that combustion gasses bypassing the nozzle disc will be minimized.

Referring now to FIG. 4, there is shown one embodiment for circulating heat transfer fluid, room air in this preferred embodiment, through the heat exchanger assembly 40 to heat the adjacent room. The preferred embodiment includes an air supply conduit 80 and an air return conduit 90. In operation, a fan/motor assembly 100 draws relatively cool air from the room and directs it through room air supply conduit 80 toward the heating medium inlet opening 84 of the heat exchanger core 42. The room air enters room the interior of inner hollow member 44 through the medium inlet opening 84 and moves through the heat exchanger cores 42 while absorbing heat from the hot combustion gases that are spinning around the outer surface of the inner hollow member 44. After passing through the heat exchanger cores 42, the room air then exits the heat exchanger assembly through a heating medium outlet opening 94 and is delivered back to the room by the return air conduit 90.

Conduit design may include adjustable and/or flexible air supply and return conduit 80, 90 to enable the plenums to be installed in a variety of fireplace sizes and configurations. While imperative for retro-fit installations where the exact fireplace dimensions are unknown when the conduits are fabricated, such flexibility may also benefit purpose-built fireplace installations by enabling a single conduit design to be used on a range of fireplace sizes. Such flexible design streamlines production and inventory requirements thereby reducing overall cost of production of the invention.

While the embodiment shown in FIG. 4 describes use of the invention for heating a room adjacent to the fireplace, other alternatives are possible by directing the air supply and return conduits to other rooms. Those skilled in the art will recognize that numerous options for directing a heat transfer medium to and through the heat exchanger assembly are permissible within the scope of the present invention. While two generally parallel flow paths are shown in FIG. 4, it is possible to direct the heat transfer medium in a series flow through the entire heat exchanger assemble wherein a single heating medium inlet opening 84 and a single heating medium outlet opening 94 is used. Conversely, more than two generally parallel flow paths may also be used since the heat exchanger cores 42 of the present invention are modular in nature. Adjusting the heating medium flow rates and the flow configuration through the heat exchanger cores allows a desired heating medium return temperature to be selected based on the heat input of the burner assembly.

In an alternate embodiment, a liquid heat transfer medium is circulated through the inner hollow members whereupon it absorbs heat energy from the hot combustion gasses. The heated liquid can then be easily conveyed to other locations where the heat energy is extracted to provide heat to a room or another area. An ideal remote location would be a heat exchanger positioned in the existing heating system for a house whereby the heat energy from the fireplace is efficiently distributed to the entire heated portion of a house or building structure. Such an application provides further benefit to heat pump systems which require a supplemental heat source when outside air temperatures fall below certain levels. Heat energy from the fireplace can replace expensive electric resistance heating elements often used as supplemental heat sources for heat pumps, potentially lowering energy costs. Due to the modular arrangement of the heat exchanger assembly, a combination of room air from a room adjacent the fireplace and a heat transfer liquid directed to a heat exchanger in a different location may be accommodated enabling a single fireplace to effectively heat greater portions of a house, thereby further increasing the effectiveness of the fireplace as a supplemental heating source.

Referring now to FIG. 5, wherein a first alternate embodiment of the present invention is shown wherein the combustion gas and heating medium turnaround adapters (62, 64 shown in FIG. 2) are eliminated and replaced by a non-linear heat exchanger core 42. In effect, the inner and outer hollow members 44, 46 are formed into a U-shape so that the heating medium inlet and outlet openings 84, 94 and the combustion gas inlet and outlet opening 86, 96 are generally adjacent. This alternate embodiment simplifies materials and construction by eliminating the turnaround adapters and associated connections in exchange for using curved hollow members in lieu of straight hollow members. It is to be expected that this first alternate embodiment will reduce production costs of the invention and simplify assembly. Flow of hot combustion gasses and heating medium are as described in the first embodiment in association with FIGS. 2 through 4. One or more nozzle discs 70 may be used in this embodiment, with the first being positioned proximate to the combustion gas inlet opening 86. As the length of the heat exchanger core 42 is increased, additional nozzle discs may be required to be positioned downstream in the annular passageway to maintain adequate rotational motion in the combustion gasses as they traverse the passageway 48 toward the combustion gas outlet opening 96. One or more assembly joints 49 may also be used to in the heat exchanger core 42 to facilitate fabrication and assembly.

It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the inventions. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown. 

1. A heat exchanger assembly for use in a fireplace having a combustion chamber, a chimney flue having an opening connected to a top portion of the combustion chamber, a heat source supported at a bottom portion of the combustion chamber for producing hot gasses in response to combustion, a front opening, a combustion air supply opening, and a fire screen assembly or the like for closing the front opening to separate the combustion chamber from a room area to be heated, the heat exchanger assembly comprising: a baffle for sealing the chimney opening, said baffle having at least one flue opening for exhausting combustion gasses into said chimney flue; at least one elongate heat exchanger core having an outer hollow member with opposing combustion gas inlet and outlet ends separated by a outer member length, and an inner hollow member disposed within and generally coextensive with said outer hollow member forming an annular passageway therebetween, said inner hollow member having a medium inlet end and a medium outlet end, and further defining an interior passageway for a heat transfer medium flowing generally from said medium inlet end toward said medium outlet end, combustion gas flow within said annular passageway being generally in a counter-flow heat exchange relationship with said medium flow within said inner hollow member, receiving combustion gasses from said combustion chamber at said gas inlet end and discharging combustion gasses from said gas outlet end; at least one nozzle disk positioned in said annular passageway and arranged to induce a swirling flow pattern of said combustion gasses about said inner hollow member generally between said combustion gas inlet and outlet ends; and a supply conduit in flow communication with said medium inlet end for directing a flow of said heat transfer medium toward said medium inlet end of said inner hollow member and a return conduit in flow communication with said medium outlet end for receiving said heat transfer medium from said medium outlet end of said inner hollow member.
 2. The heat exchanger of claim 1, wherein said heat transfer medium is air.
 3. The heat exchanger of claim 1, wherein said heat transfer medium is a liquid,
 4. The heat exchanger assembly of claim 1, further comprising: at least one fluid crossover connecting a plurality of said inner hollow members thereby forming a continuous conduit through said plurality of inner hollow members, said continuous conduit receiving a flow of said heat transfer medium at an conduit inlet and discharging said flow from a conduit discharge, and at least one combustion gas crossover connecting a plurality of said annular passageways thereby forming a continuous passageway through said plurality of annular passageways, said continuous passageway receiving a flow of said combustion gasses from said combustion chamber at a passageway inlet and discharging said combustion gasses from a passageway outlet generally toward said flue opening, flows of said heat transfer medium and said combustion gasses being in generally opposite directions in a counterflow heat exchange relationship.
 5. The heat exchanger assembly of claim 1 further comprising an air supply distributor positioned below the heat source for directing combustion air flow from the combustion air supply opening toward the front opening.
 6. The heat exchanger assembly of claim 1, wherein said supply conduit and said return conduit are adjustable to fit fireplaces of various sizes.
 7. The heat exchanger assembly of claim 6, wherein a portion of said supply 2 and said return conduits is made of a flexible material.
 8. The heat exchanger assembly of claim 1, wherein said swirling flow pattern induced by said nozzle disk is in the same direction as that caused by the earth's Coriolis force.
 9. The heat exchanger assembly of claim 1, wherein at least one elongate heat exchanger core is generally vertically oriented to maximize the Goriolis effect.
 10. The heat exchanger assembly of claim 1, wherein said inner hollow member is made of aluminum.
 11. The heat exchanger assembly of claim 1, wherein said outer hollow member is made of steel.
 12. The heat exchanger assembly of claim 1, further comprising a radiant energy reflector positioned to reflect combustion flames toward the front opening.
 13. The heat exchanger assembly of claim 4, further comprising an air supply distributor positioned below the heat source for directing combustion air flow from the combustion air supply opening toward the front opening.
 14. The heat exchanger assembly of claim 13, wherein said swirling flow pattern induced by said nozzle disk is in the same direction as that caused by the earth's Coriolis force.
 15. The heat exchanger assembly of claim 14, wherein at least one elongate heat exchanger core is generally vertically oriented to maximize the Coriolis effect.
 16. The heat exchanger assembly of claim 15, wherein said supply conduit and said return conduit are adjustable to fit fireplaces of various sizes.
 17. The heat exchanger assembly of claim 16, wherein a portion of said supply and said return conduits are made of a flexible material.
 18. The heat exchanger assembly of claim 17, wherein said inner hollow member is made of aluminum.
 19. The heat exchanger assembly of claim 18, wherein said outer hollow member is made of steel.
 20. The heat exchanger assembly of claim 19, further comprising a radiant energy reflector positioned to reflect combustion flames toward the front opening.
 21. The heat exchanger of claim 20, wherein said heat transfer medium is air.
 22. The heat exchanger of claim 20, wherein said heat transfer medium is a liquid.
 23. A method of heating room air using a fireplace having a combustion chamber, a chimney flue having an opening connected to a top portion of the combustion chamber, a heat source supported at a bottom portion of the combustion chamber for producing hot gasses in response to combustion, a front opening, a combustion air supply opening, and a fire screen or the like for closing the front opening to separate the combustion chamber from a room area to be heated; the method comprising the steps. providing a baffle for sealing the chimney opening, the baffle having at least one flue opening for exhausting combustion gasses into the chimney flue; to providing at least one elongate heat exchanger core having an outer hollow member with opposing combustion gas inlet and outlet ends separated by a outer member length, and an inner hollow member disposed within and generally coextensive with said outer hollow member forming an annular passageway therebetween, the inner hollow member having a medium inlet end and a medium outlet end, and further defining an interior passageway for a heat transfer medium flowing generally from the medium inlet end toward said medium outlet end, combustion gas flow within the annular passageway being generally in a counter-flow heat exchange relationship with the medium flow within the inner hollow member, receiving combustion gasses from the combustion chamber at the gas inlet end and discharging combustion gasses from the gas outlet end, and at least one nozzle disk positioned in the annular passageway proximate the combustion gas inlet to induce a swirling flow pattern of the combustion gasses about said inner hollow member generally between the combustion gas inlet and outlet ends, providing a supply conduit in flow communication with the medium inlet end for directing a flow of the heat transfer medium toward the medium inlet end of the inner hollow member and a return conduit in flow communication with the medium outlet end for receiving the heat transfer medium from the medium outlet end of the inner hollow member and directing it toward a desired location to be heated; providing a source of heat input to the fireplace in the form of a combustion process; heating the air within the combustion chamber by the combustion process and passing the heated combustion gasses through the annular passageway with a swirling motion caused by the at least one nozzle disc; and passing a heat transfer medium through the inner hollow member by way of the supply and return conduits, whereby relatively cool heat transfer medium supplied to the inner hollow member is heated and subsequently returned to the desired location to be heated.
 24. The method of claim 19, wherein the heat transfer medium is room air and the desired location to be heated is a room. 